This invention concerns the field of protection of hydrocarbon-production equipment, and, in particular, equipment located downstream from submarine well heads and/or equipment located on off-shore platforms (manned or unmanned).
The effluents collected at the outlet of an oil well are normally of the multiphase type; that is, they contain a mixture of gas, liquid, and potentially, solids. The effluents are circulated through a pipeline either to facilities on the coastline or to a treatment platform. Because of the instability of the multiphase flows, liquid plugs and/or gas pockets of fairly significant lengths inevitably form inside the pipelines. At the end of the pipeline, the transported fluid enters a separation tank, in which natural decantation of the multiphase fluid into its different phases is carried out. The liquid phase is extracted from the bottom of the tank and transported to separation and treatment equipment, while the gaseous phase is removed at the upper part of the tank and is treated and compressed before being used locally or shipped.
Patent No. EP-0 465 032 discloses a non-intrusive measurement system used to monitor flows of multiphase fluids containing plugs in a pipeline. However, in this system no active excitation of the pipeline is carried out, but rather, using external sensors, noise generated directly by the passage of the plugs in the pipeline is passively monitored. Moreover, this system incorporates no control means making it possible to regulate the intake valves of the equipment used to treat the gaseous and liquid phases.
Patent No. WO-A-89 05974 concerns a system for analyzing the composition of a multiphase fluid circulating in a pipeline. However, this system includes intrusive means for generating turbulence or cavitation noise in the fluid, in particular an impact valve. In addition, it does not incorporate mechanisms for controlling the intake valves in the treatment equipment. Patent No. WO-A-93 14382 raises the same problems.
Patent WO-A-93 24811 relates to a non-intrusive system for measurement of gas, oil, and water mass flow rates in multiphase flows containing plugs. Excitation is not, however, generated by a mechanical or acoustic excitation apparatus, but by a radioactive gamma ray source.